Showing papers in "Center for the Built Environment in 2007"

Climate Change 2007: The Physical Science Basis.

Abstract: Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

Climate Change 2007: Impacts, Adaptation and Vulnerability.

Abstract: Impatti, adattamento e vulnerabilita Le cause e le responsabilita dei cambiamenti climatici sono state trattate sul numero di ottobre della rivista Cda. Approfondiamo l’argomento presentando il documento: “Cambiamenti climatici 2007: impatti, adattamento e vulnerabilita” votato ad aprile 2007 dal secondo gruppo di lavoro del Comitato Intergovernativo sui Cambiamenti Climatici (Intergovernmental Panel on Climate Change). Si tratta del secondo di tre documenti che compongono il quarto rapporto sui cambiamenti climatici.

Climate Change 2007: Mitigation of Climate Change.

Abstract: Politiche, misure e strumenti per contenere le emissioni di CO2 Illustriamo l’ultimo contributo al quarto Rapporto sui cambiamenti climatici votato a maggio 2007 dal terzo gruppo di lavoro del Comitato intergovernativo “Intergovernmental Panel on Climate Change”. Il Rapporto affronta la problematica delle tendenze delle emissioni dei gas serra e il tema della mitigazione a breve e lungo termine. Presentiamo un’analisi critica delle proposte del documento.

Air movement preferences observed in office buildings

Abstract: Office workers’ preferences for air movement have been extracted from a database of indoor environmental quality surveys performed in over 200 buildings. Dissatisfaction with the amount of air motion is very common, with too little air movement cited far more commonly than too much air movement. Workers were also surveyed in a detailed two-season study of a single naturally ventilated building. About half the building’s population wanted more air movement and only 4% wanted less. This same ratio applied when the air movement in workspaces was higher than 0.2 m/s, the de facto draft limit in the current ASHRAE and ISO thermal environment standards. Preference for “less air motion” exceeded that for “more” only at thermal sensations of -2 (cool) or colder. These results raise questions about the consequences of the ASHRAE and ISO standards’ restrictions on air movement, especially for neutral and warm conditions.

An Index for Evaluation of Air Quality Improvement in Rooms with Personalized Ventilation Based on Occupied Density and Normalized Concentration

Abstract: The personal ventilation (PV) system decreases the pollutant concentration mostly in the microenvironment at the workstation, but it can also increase the contaminant in other zone of the room. Therefore, occupant’s exposure to pollutant depends on the ratio of time occupant stays at the workstation over total time he/she stays in the room. This ratio is named occupied density (OD). An index, using a modified definition of OD, is developed to compare and quantify the variation in terms of inhaled pollution by occupant in a room with PV in conjunction with a total-volume ventilation system. The index is applied to data collected during full-scale room measurements. The results show that the index can be used at the design stage for assessment the benefit of PV when applied in practice for office buildings with different OD. It is for example demonstrated that if the occupied density is lower than 0.5 the use of displacement ventilation alone will be advantageous with regard to human-produced contaminates in comparison when it is combined with PV system.

Simulated energy savings of cool roofs applied to industrial premises in the Mediterranean Area

Abstract: Cooling energy savings and improved thermal comfort in hot climates can be achieved using cool roofing materials. High solar reflectance and infrared emittance values reduce the amount of absorbed solar radiation and the surface temperature of a material exposed to sun radiation, consequently the heat transfer into the building is lowered. A reduction of the urban heat island effect, caused by the presence of high absorption surfaces and the lack of vegetation, may be obtained using cool roofing materials. Computer energy simulations have been used to assess the energy savings and temperature profiles consequent to the application of a cool roofing material when applied to industrial premises in three Mediterranean cities: Genoa, Madrid and Cairo. In particular, the related influence on cooling energy demand and maximum temperature at the outside face of the roof are analyzed, varying the roofing material and the insulation thickness. The results of this study showed that using a cool roofing material in the Mediterranean area for industrial premises leads to significant sensible cooling energy savings, up to 42%. Moreover, it was obtained that the maximum roof outside surface temperatures decrease of 40÷50°C when cool roofing materials are applied.